You can change its color, length, size, warp it, connect it with other lines. The only thing you can't do is change the dot distance. In this sequence: Connecting a normal line first, then a dotted line will make it all normal. Connecting a dotted line first, then a normal line will make it all dotted.
So, they clearly CAN give us dotted lines, but they just don't give a fuh like, they could give us a lot, but do they care? no, to them this is just a site for 8 to 6 year olds, and not a free opportunity for people to animate who don't know, nor have the money for a better program. It sucks really. You can use this for dotted lines if you need, just backpack this costume, or download the copy button as an SVG.